Developing strategies for recognizing and treating children with Sleep Disordered Breathing (SDB) is not possible in the absence of essential epidemiological data that address the distribution of measures of SDB in pediatric populations. The potential public health importance of this is underscored by preliminary data that suggest that risk of SDB is increased in susceptible populations, in particular, in African Americans and in children born prematurely. The goals of this study are to collect fundamental data regarding the distribution of measures of SDB in a pediatric population, prevalence of clinically significant SDB in children risk factors, and associated co-morbidity. In this cohort study with a nested case control arm, we will exploit access to a well-characterized cohort of 8 to 10 year olds (50% born prematurely) who have participated in longitudinal studies of behavior and cognition. The cohort consists of a birth cohort (1988-1993). SDB will be evaluated in 850 children with in-home state-of the art monitoring techniques, measuring abdominal and thoracic movement, oxygen saturation, movement, body position, and ECG. A broad array of risk factors will be evaluated: sociodemographic characteristics; upper and lower airway size and function (questionnaire, spirometry, acoustic pharygometry and rhinometry); perinatal exposures (from neonatal records); family history; and home environment (passive smoking; sleep patterns, maternal-child stress indices). Behavior, cognitive skills, attention, and health-related quality of life will be assessed with standardized instruments to assess co-morbidities (potential SDB outcomes). A case-control arm will provide more detailed data for three groups of children: definite SDB by home assessment; equivocal SDB; and no SDB. In this arm, children will be studied with conventional overnight in-laboratory polysomnography (in the GCRC), daytime Multiple Sleep Latency Tests, and cephalometry. Its purposes are to confirm and extend the findings of the in-home assessments with comprehensive laboratory studies and objective measures of sleepiness. Collection of a comprehensive data set will help identify which measures best discriminate symptomatic (e.g., snoring, sleepy) from asymptomatic children. Comprehensive risk factor and outcome data should improve strategies for identifying and intervening in high risk children. Follow-up of a cohort with a large number of preterm children also affords an excellent opportunity to study SDB co-morbidities in a group at high risk for developmental delays (who may be susceptible to additive adverse effects of SDB) and to explore new hypotheses regarding the role of developmental factors in SDB.